SequenceEqualBenchmark.cs

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using nint = System.Int64;

public class SequenceEqualThreshold
{
    static void Main(string[] args)
    {
        BenchmarkSwitcher.FromAssembly(typeof(SequenceEqualThreshold).Assembly).Run(args);
    }

    private GCHandle _inputHandle;
    private Memory<byte> _input;
    private GCHandle _expectedHandle;
    private Memory<byte> _expected;

    [Params(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 80, 96, 128, 192, 256, 512, 1024, 2048, 4096)]
    public int Length;

    [GlobalSetup]
    public void Setup()
    {
        var overlength = Length + 4096;
        var input = new byte[overlength];
        var expected = new byte[overlength];

        // Need to keep alignment the same between methods and runs
        _inputHandle = GCHandle.Alloc(input, GCHandleType.Pinned);
        _expectedHandle = GCHandle.Alloc(expected, GCHandleType.Pinned);

        var inputOffset = 4096 - (int)((nint)_inputHandle.AddrOfPinnedObject() & 4095);
        var expectedOffset = 4096 - (int)((nint)_expectedHandle.AddrOfPinnedObject() & 4095);

        _input = new Memory<byte>(input, inputOffset, Length);
        _expected = new Memory<byte>(expected, expectedOffset, Length);

        var inputSpan = _input.Span;
        var outputSpan = _expected.Span;
        for (int i = 0; i < Length; i++)
        {
            var value = (byte)i;
            inputSpan[i] = value;
            outputSpan[i] = value;
        }
    }

    [Benchmark]
    public bool UseLinearSearch()
    {
        if (!LinearSearch(_input.Span, _expected.Span))
        {
            throw new Exception();
        }

        return true;
    }

    [Benchmark]
    public bool UseSequenceEqual()
    {
        if (!_input.Span.SequenceEqual(_expected.Span))
        {
            throw new Exception();
        }

        return true;
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static bool LinearSearch(Span<byte> input, Span<byte> expected)
    {
        if (input.Length != expected.Length)
        {
            return false;
        }

        for (int i = 0; i < input.Length; i++)
        {
            if (input[i] != expected[i])
            {
                return false;
            }
        }
        return true;
    }
}